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ARRL Propagation Bulletin ARLP024 (2010)

ARLP024 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 24  ARLP024
From Tad Cook, K7RA
Seattle, WA  June 18, 2010
To all radio amateurs 

ARLP024 Propagation de K7RA

Average daily sunspot numbers were up 2.5 points from last week,
despite the fact that there were no sunspots at all this week on
June 15-16.  A new sunspot group 1082 emerged yesterday, June 17,
and yielded a daily sunspot number of 14.  A nice thing about this
spot is that it is all the way over on the east side of the visible
solar disk, meaning we will probably see its effects as it moves
across the sun.  All other recent sunspots emerged toward the west
side, which meant that they went over the horizon fairly quickly and

Last week there were four sunspot groups visible at different times.
Group 1078 disappeared on June 12, 1079 and 1080 both were gone on
June 14, and on June 15 1081 was gone.  Geomagnetic activity peaked
on June 16 with the planetary A index at 19 and high latitude
college A index at 42.  This should decline over the next couple of

We did not receive a prediction from Geophysical Institute Prague
this week, but NOAA/USAF say that the expected planetary A index for
June 18-28 is 10, 5, 5, 5, 5, 5, 8, 12, 15, 15 and 8.  This shows
unsettled to active geomagnetic conditions for Field Day weekend,
June 26-27.  The same prediction shows solar flux at 70 on June
18-24, then 75 for June 25-30.

Glen Stuart, N7NRA of Mesa, Arizona sent this in about recent 10
meter activity.  "N7YU, Dave, in Chandler, AZ, and I had QSOs into
Rarotonga last evening on 28.445 at about 0045Z, 14 June.  The op on
the other end was E51JD, Jim.  There was some QSB, but we were
reporting 57 on both ends.  I don't know how much power Dave was
running.  I was using 100W.  We both use Butternut HF-9Vs.  His is
ground mounted, mine is roof mounted with the base at about 15 feet
above ground.  When I built my shop I had the roofers install a
carpet of chicken wire between the shingles and the tar paper. My
counterpoise is about 16 x 50 feet and works well. Things are
looking up for the higher frequencies".

On that same date, June 14, the K0KP six-meter beacon was copied in
the Netherlands.  Rex Greenwell, K0KP lives in Duluth and operates a
100 watt beacon on 50.073 MHz at the 50 foot level on a commercial
broadcast tower in grid square EN36wt.  Here is the message from

"This is an email I received from PF7M today - Netherlands.  This
was at 01:50 AM Central time.  6M - Europe to Minnesota in the wee
hours of the AM. - Rex K0KP EN36 20 mi. NW of Duluth, MN.

Hello Rex, This morning round 06.50 UTC I have received your K0KP/B
beacon on 50.073MHZ. Just audible at 419 with my 6 element Yagi at
20 meters.  Locator here: JO33BA.  6 meters was open from here to GM
and OY, so think it was some extended Es into EN36.  Not any NA
present on 6M at this time.  73's Johan - PF7M"

Several readers sent in links to articles on our sun's recent
strange behavior, including this one, and
this one on the NASA Solar Observatory.  In
last week's bulletin we raised the question about adjusted solar
flux values, and why they are adjusted to compensate for the
variation in the distance between earth and sun.  The solar flux
values we present here are the values as measured at the observatory
in Penticton, British Columbia.  You can see them at  They come from the 2000z reading in the
third column from right, with the heading fluxobsflux.  The next
column to the right, fluxadjflux, is the adjusted value.  They are
adjusted up or down to reflect a value based on the average distance
of our planet from our sun.

On 6-17-2010 at 2000z the raw observed value was 70.4, and the
adjusted value was 72.7.  This is because we are now further away
from the sun than other times of the year.  Of course, we are
interested in the observed value, because that is a measure of the
radiation hitting our ionosphere.  But if we wanted to keep track of
adjusted solar flux to gauge solar activity, this would show us more
realistically what the sun is actually doing.  Back on April 5 the
observed and adjusted readings show the same value, but in January,
we were closer to the sun, so the value was adjusted downward.

This weekend is the All Asia CW DX Contest, and HF conditions should
be fair.  There are no predicted geomagnetic disturbances.

The new issue of WorldRadio online should be out this Sunday, June
20, and there is always an informative column on propagation by
K9LA.  Check it on Sunday at
If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see the ARRL
Technical Information Service at For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at  Monthly
propagation charts between four USA regions and twelve overseas
locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for June 10 through 16 were 41, 43, 46, 46, 12, 0,
and 0 with a mean of 26.9.  10.7 cm flux was 72.9, 74.6, 76.2, 76.3,
72.8, 70.1 and 71.6 with a mean of 73.5.  Estimated planetary A
indices were 6, 5, 3, 6, 5, 10 and 19 with a mean of 7.7.  Estimated
mid-latitude A indices were 5, 4, 1, 5, 3, 9 and 13 with a mean of


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